Prescriptions for ophthalmic lenses vary widely, of course, so it is impractical for any eye care professional to stock finished lenses, especially finished multifocal, finished progressive, and finished aspheric lenses. Multifocal and progressive lenses provide not only distance and near vision correction, but also astigmatic correction through 180 degrees of rotation, and are generally specific to left or right eyes. However, prescription finished single vision and multifocal ophthalmic lenses can be made by adhering together a pair of lens wafers at differing positions of adjustment therebetween. Accordingly, eye care professionals often carry large inventories of lens wafers so that finished lenses can be made therefrom. Unfortunately, the possible range of prescriptions is infinite for all practical purposes, so the number of lens wafers that must be carried in inventory is still very large.
More importantly, the making of a finished prescription lens by adhering together a couple of lens wafers is not a simple task. Even the cleanest, most careful labs commonly produce lens having dirt particles trapped therein, bubbles formed therein, improper alignment of the two wafers relative to each other, and other unacceptable characteristics.
The conventional wisdom has been to address these problems by developing better optical adhesives, better tools, and the like. Although such developments have been worthwhile, the industry is still plagued with large inventories of lens wafers and an unacceptably high rate of lens rejection.
There is a clear need, then, for an entirely new approach to the problem. What the new approach might be is not ascertainable by any study of the prior art.